Topologically tuned terahertz confinement in a nonlinear photonic chip

Abstract

Compact terahertz (THz) functional devices are greatly sought after for high-speed wireless communication, biochemical sensing, and non-destructive inspection. However, controlled THz generation, along with transport and detection, has remained a challenge especially for chip-scale devices due to low-coupling efficiency and unavoidable absorption losses. Here, based on the topological protection of electromagnetic waves, we demonstrate nonlinear generation and topologically tuned confinement of THz waves in an engineered lithium niobate chip forming a wedge-shaped Su–Schrieffer–Heeger lattice. Experimentally measured band structures provide direct visualization of the THz localization in the momentum space, while robustness of the confined mode against chiral perturbations is also analyzed and compared for both topologically trivial and nontrivial regimes. Such topological control of THz waves may bring about new possibilities in the realization of THz integrated circuits, promising for advanced photonic applications.

Tunable Topological Lasing of Circularly Polarized Light in a Soft‐Matter‐Based Superlattice

“…It is also the same in the structure by directly concatenating two SSH lattices with different topological properties, as shown in refs. [51][52][53]. Thus, the construction of the SSD structure is more comprehensive, because the SSD structure also allows for topologically trivial defect states on both sides of the mini-bands due to the high refractive index region formed by three closely spaced ribbons at the interface.…”

“…In this work, we establish a photonic structure consisting of an assembly of laser active polymer ribbons forming a topological Su-Schrieffer-Heeger (SSH) lattice [47][48][49][50][51][52][53][54][55][56] filled with a CLC. Such polymer CLC (P-CLC) lattices are fabricated to contain a short-short defect (SSD) at the interface between topologically trivial and nontrivial regimes.…”

“…Such polymer CLC (P-CLC) lattices are fabricated to contain a short-short defect (SSD) at the interface between topologically trivial and nontrivial regimes. [51][52][53] The remarkable point is that a pure micro-sized periodic polymer ribbon structure has a first bandgap at micron scale. When it is immersed in a CLC, it will open up mini-bandgaps at visible wavelength region in the photonic bandgap of the CLC.…”

Switching Chirality in Arrays of Shape‐Reconfigurable Spindle Microparticles

“…When photocurrent is selectively switched along the light propagation direction in the terahertz (THz) regime, we could explore potential applications in security, biomedical imaging, wireless communication, and photonic computing. [24][25][26] Although chiral switches of metamaterials have been reported for THz polarization modulation, [27][28][29] for example, through deformation of a chiral microelectromechanical system (MEMS) pneumatically, those systems are typically based on hard materials and require large forces to induce deformation. More importantly, it remains challenging to achieve local deformation in currently reported approaches, which will be especially critical to realize topological transitions between the trivial and nontrivial photonic phases.…”

Terahertz waveform synthesis in integrated thin-film lithium niobate platform

“…Early work recognized that miniaturization may provide solutions to these issues, such as, e.g., ion slicing bulk crystals into thinner slabs 42 . With advances in nanostructuring TFLN 23 , few theoretical proposals to generate THz radiation appeared recently 43 , along with experimental proposals of using topological confinement in laser-written LN slabs 44 .…”